1. Technical Field
The present invention generally relates to a light emitting diode (LED) light source and, in particular, to a tube type LED light source.
2. Description of the Related Art
A liquid crystal display (LCD) is a non-self luminescent flat panel display which includes a flat light source device. The flat light source device is a so-called backlight module. There are two types of backlight modules: direct-light type and edge-light type backlight modules. A conventional direct-light type backlight module comprises a plurality of light tubes (such as cold cathode fluorescent lamps), a diffuser sheet, a prism sheet, and so on. Light generated from the light tubes is reflected back or partially absorbed when travelling through the diffuser sheet, and therefore the transmittance of light is reduced. Besides, the performance of the cold cathode fluorescent lamps is unstable and will cause the backlight module to have a dark region if any of the cold cathode fluorescent lamps is failed. Moreover, it can be understood from FIG. 1 that the illumination provided by the backlight module is un-uniform and the smaller the distance between the diffuser 102 and the corresponding cold cathode fluorescent lamps 101 is, the more un-uniform the illumination provided by the backlight module is.
To scatter the light uniformly to serve as a light source for LCD devices, the distance between every light source should be controlled precisely, and the distance between the light sources and the diffuser or the prism sheet should be increased, and then the thickness of the backlight module is increased accordingly to avoid uneven brightness distribution.